Motor centrifugal pump

ABSTRACT

The invention relates to a motor centrifugal pump having a plastic-injection-moulded stator core of the electric motor, wherein cooling channels are arranged in the plastic, through which channels the conveying medium flows.

The invention relates to a motor centrifugal pump having a plasticextrusion-coated stator core for the electric motor.

Extrusion coating of the stator core of an electric motor with plasticis known. One drawback of such extrusion coating is that the plasticused represents a good thermal insulator. The embedded stator issubjected to high thermal stress, and it is difficult to release largeamount of high heat to the surroundings or to the coolant. Furthermore,the known wet rotor pumps for heating water and service water arecomposed of numerous parts that must be assembled. A large number ofinstallation steps is necessary in particular for assembly of theencapsulated electric motor.

The object of the invention is to reduce the temperature of the statorand in particular also of the motor electronics system for motorcentrifugal pumps of the above-described type, by use of a simpledesign.

This object is achieved according to the invention by forming theplastic with cooling passages through which the pumping medium flows.

In this manner the high temperatures at the stator and the electronicssystem needed for regulating and controlling the pump are reduced by useof medium-filled cooling passages or chambers. Extrusion coating of theelectric stator greatly reduces the number of individual parts, and thusminimizes manufacturing and installation effort. Several functions areprovided by the extrusion coating.

Advantageous embodiments of the invention are given in the dependentclaims.

Four illustrated embodiments of the invention are illustrated in thedrawing and described in greater detail below.

In the drawing:

FIG. 1 is an axial section of a first illustrated embodiment of anelectric motor with a pump impeller;

FIG. 2 is an axial section of a second illustrated embodiment of anelectric motor with a pump impeller;

FIG. 3 is an axial section of a third illustrated embodiment of anelectric motor with a pump impeller; and

FIG. 4 is a cross section of a fourth illustrated embodiment of anelectric motor.

The motor centrifugal pump has a motor shaft 1 having a motor axis 2.The motor shaft 1 is supported in two radial bearings 3 and 4 and oneaxial bearing 5 inside the rotor compartment 6. On the hydraulic sidethe motor shaft 1 projects from the electric motor, and at this endcarries the pump impeller 7 that is inside the pump housing (notillustrated).

The rotor 8 is fixed to the shaft 1 in the rotor compartment 6, which inturn is surrounded by windings 9 and a stator core 10.

The rotor compartment 6, windings 9, and stator core 10 are imbedded ina plastic mass 11 that is introduced, in particular injected, betweenthese parts in the form of a filling compound, and that preferably formsthe inner wall of the rotor compartment 6, so that an additional splitcase is not necessary since the plastic forms the split case. Inaddition, it is not necessary for the plastic mass to be surrounded byan external motor housing; instead, the plastic itself may form theexterior of the motor.

Formed in the plastic mass 11, outside of and next to the rotorcompartment 6 and parallel to the motor axis 2, are cooling passages orcooling chambers 12 that are preferably situated between the windings 9and connected to the pump chamber on the hydraulic side via openings(not illustrated), so that the pumping medium moved by the pump impeller7 for cooling the motor flows through the cooling passages 12.

As shown in the embodiment of FIG. 2, it is not absolutely necessary forthe cooling passages 12 to be connected to one another; instead,sufficient medium exchange with the pump chamber may occur within thecooling passage through the connecting opening or openings in thecooling passage. In the illustrated embodiment according to FIG. 1,however, the cooling passages 12 are connected to one another viatransverse passages or a transverse chamber 13 situated on the end ofthe motor facing away from the pump impeller 7, outside the rotorcompartment 6. The transverse chamber 13 is sealed off by a lid-shapedelement 14, in particular made of plastic, which separates the interiorof an electronics housing 15 from the motor interior. The board 16 ofthe motor electronics system lies against the outer side of thiscircular part 14 from which the motor axis 2 extends perpendicularly, sothat the electronic parts are cooled by the liquid in the transversechamber 13.

The electronics housing 15 is preferably fastened to the plastic mass 11by means of screws 17 extending parallel to the motor axis 2. Theelectronics housing 15 is thus fastened on the end of the motor facingaway from the hydraulic area.

The transverse chamber 14 is connected to the rotor compartment 6 via anopening, in particular a coaxial passage 18, so that the pumped liquidflows through the cooling passages 12, the transverse chamber 13, thepassage 18, and the rotor compartment 6, and back to the pump chambervia openings (not illustrated). The illustrated embodiment according toFIG. 3 shows that a design is also possible in which there is noconnection between the transverse chamber 13 and the rotor compartment6. Inside the rotor compartment 6, on the side facing away from the pumpimpeller 7 and thus close to the transverse chamber 13, coaxially moldedonto the plastic mass 11 is a plastic collar 19 in which the radialbearing 4 rests, so that the collar 19 forms a secure seat for thisbearing. In addition, the other bearings may optionally or additionallybe held by projecting parts of the plastic mass 11.

FIG. 4 illustrates sections of the illustrated embodiments according toFIGS. 1 through 3, and shows a triangular cross-sectional shape of thecooling passages. In other designs not illustrated, the cooling passagesmay have other cross-sectional shapes, and may also be connected to oneanother via other connecting passages (not illustrated) to form one,two, or more circuits.

1. A motor centrifugal pump having a plastic extrusion-coated stator core for the electric motor wherein the plastic is formed with cooling passages through which the pumping medium flows.
 2. The pump according to claim 1 wherein the cooling passages extend at least partly parallel to the motor axis.
 3. The pump according to claim 1 wherein at least parts of the cooling passages extend between the motor windings.
 4. The pump according to claim 1 wherein the cooling passages are connected via one, two, or more passages to the pump chamber conducting the pumping medium.
 5. The pump according to claim 1 wherein the cooling passages are connected to one another.
 6. The pump according to claim 1 wherein the cooling passages have no connection to the pump chamber, and form a circuit inside the motor.
 7. The pump according to claim 1 wherein at least one cooling passage extends past the electronics system of the motor in a closed circuit.
 8. The pump according to claim 1 wherein the plate for the motor electronics system is mounted on the plastic, close to at least one cooling passage.
 9. The pump according to claim 1 wherein at least one cooling passage on the side of the motor facing away from the pump impeller is closed off and sealed by a lid-shaped element made of plastic or metal.
 10. The pump according to claim 9 wherein the plate for the motor electronics system lies against the exterior of the lid-shaped element for cooling.
 11. The pump according to claim 1 wherein the plastic also forms the split case.
 12. The pump according to claim 1 wherein the plastic forms the exterior of the motor.
 13. The pump according to claim 1 wherein the housing for the electronics system is fastened to the plastic.
 14. A method of making a pump according to claim 1 wherein the plastic is injected into gaps in the stator and forms the cooling passages. 